Muslim conquests following Prophet Muhammad's death led to the creation of the caliphates, occupying a vast geographical area; conversion to Islam was boosted by missionary activities, particularly those of Imams, who intermingled with local populations to propagate the religious teachings. These early caliphates, coupled with Muslim economics and trading and Islamic Golden Age and the later expansion of the Gunpowder Empires, resulted in Islam's spread outwards from Mecca towards the Indian, Atlantic, and Pacific Oceans and the creation of the Muslim world. Trading played an important role in the spread of Islam in several parts of the world, notably Indian traders in southeast Asia.